Prenatal exposure to per- and polyfluoroalkyl substances and risk of autism spectrum disorder in the California Central Valley, 2004–2010

Background: There is mixed evidence regarding the association between per- and polyfluoroalkyl substances (PFAS) and autism spectrum disorder (ASD). Methods: We matched 294 ASD cases to 286 controls by sex, birth year, and exposure to selected pesticides and air pollution. All participants were born in the California Central Valley from 2004 to 2010. Using high-resolution metabolomic profiling, three PFAS were measured in >60% of maternal serum samples: perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid, and perfluorooctane sulfonate (PFOS). Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated using logistic regression to examine relationships between PFAS and ASD. Nonlinear associations were examined using restricted cubic spline regression, and a quantile-based g-computation approach was utilized to examine the association between a PFAS mixture and ASD. Results: -shaped exposure-outcome relationship for PFOA. No apparent associations were found for the PFAS mixture and ASD. Maternal education modified associations for PFOA and PFOS; among children of mothers with lower education levels, the highest PFOA quartile was strongly associated with ASD compared with the lowest quartile (aOR = 2.97; 95% CI = 1.43, 6.18). This association was not seen with higher education levels (aOR = 0.62; 95% CI = 0.24, 1.64). Conclusions: We found that prenatal exposure to PFOA was associated with ASD in children, particularly among mothers with lower education levels. Larger studies are warranted to replicate our findings.